MCQs in Antennas Part III

(Last Updated On: December 8, 2017)

MCQs in Antennas - Part III

This is the Multiples Choice Questions Part 3 of the Series in Antennas as one of the Communications Engineering topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies, Communications Books, Journals and other Communications References.

Online Questions and Answer Topic Outline

  • MCQs in Basic considerations
  • MCQs in Wire Radiators in Space
  • MCQs in Isotropic Radiator
  • MCQs in Current and Voltage Distributions
  • MCQs in Resonant and Non-resonant Antennas
  • MCQs in Antenna Terms and Definition
  • MCQs in Antenna Gain and Resistance
  • MCQs in Bandwidth, Beamwidth and Polarization
  • MCQs in Grounded and Ungrounded Antennas
  • MCQs in Grounding Systems and Matching Systems
  • MCQs in Antenna Types
  • MCQs in Directional and Non-directional Antennas
  • MCQs in Microwave Antennas
  • MCQs in Wideband and Special Purpose Antennas

MCQs in Antennas Series

Following is the list of multiple choice questions in this brand new series:

Antennas MCQs
PART 1: MCQs from Number 1 – 50                        Answer key: PART I
PART 2: MCQs from Number 51 – 100                   Answer key: PART II
PART 3: MCQs from Number 101 – 150                 Answer key: PART III
PART 4: MCQs from Number 151 – 200                 Answer key: PART IV
PART 5: MCQs from Number 201 – 250                 Answer key: PART V
PART 6: MCQs from Number 251 – 300                 Answer key: PART VI
PART 7: MCQs from Number 301 – 350                 Answer key: PART VII
PART 8: MCQs from Number 351 – 400                 Answer key: PART VIII
PART 9: MCQs from Number 401 – 450                 Answer key: PART IX
PART 10: MCQs from Number 451 – 500                 Answer key: PART X

Continue Practice Exam Test Questions Part III of the Series

101. Stacking antenna elements

  • A. increases sensitivity to weak signals
  • B. will suppress odd harmonics
  • C. decrease signal to noise ratio
  • D. increases selectivity

102. In the case if Marconi antenna, the actual length if the radiating element is

  • A. one-half wavelength
  • B. one-quarter wavelength
  • C. one wavelength
  • D. one-eight wavelength

103. The antenna efficiency of an HF grounded vertical antenna can be made comparable to that of a half-wave antenna

  • A. By installing a good ground radial system
  • B. By isolating the coax shield from ground
  • C. By shortening the vertical
  • D. By lengthening the vertical

104. An antenna “efficiency” is computed by using one of the following equations.

  • A. Efficiency = (radiation resistance / transmission resistance)
  • B. Efficiency = (total resistance / radiation resistance) x 100%
  • C. Efficiency = (effective radiated power / transmitter output) x 100%
  • D. Efficiency = (radiation resistance / total resistance) x 100%

105. Increasing the resonant frequency of an end-fed Marconi antenna can be done by

  • A. adding a capacitor in series and reducing the physical length
  • B. adding an inductor in series
  • C. adding an inductor in series
  • D. All of these

106. Factors that determine the radiation resistance of an antenna

  • A. Transmission line length and height of antenna
  • B. The location of the antenna with respect to nearby objects
  • C. It is a constant for all antennas since it is physical
  • D. Sunspot activity and the time of day

107. _____ is the angle between the half-power radiation points

  • A. Critical angle
  • B. Beamwidth
  • C. Angle of elevation
  • D. Azimuth

108. What is the ratio of the maximum radiation intensity to the average radiation intensity?

  • A. Aperture gain
  • B. Directivity gain
  • C. Transmission gain
  • D. Power gain

109. Good grounding is important for

  • A. horizontal antennas
  • B. broadside array antennas
  • C. vertical antennas
  • D. Yagi-Uda antennas

110. An ungrounded antenna near the ground

  • A. acts as a single antenna of twice the height
  • B. is unlikely to need an earth mat
  • C. acts as antenna array
  • D. must be horizontally polarized

111. One of the following is very useful as a multiband HF receiving antenna.

  • A. Parabolic antenna
  • B. Elementary doublet
  • C. Log-periodic
  • D. Square loop

112. Which of the following antennas is best excited from a waveguide?

  • A. Biconical
  • B. Horn
  • C. Helical
  • D. Discone

113. Indicate which of the following reasons for using metal counterpoise with antennas is false.

  • A. Impossibly of a good ground connection
  • B. Protection of personnel working underneath
  • C. Provision of an earth for the antenna
  • D. Rockiness of the ground itself

114. Not a reason for the use of an antenna coupler.

  • A. To make the antenna look resistive
  • B. To provide the output amplifier with the correct load impedance
  • C. To discriminate against harmonics
  • D. To prevent re-radiation of the local oscillator

115. Which antenna is not a wideband?

  • A. Discone
  • B. Folded dipole
  • C. Helical
  • D. Marconi

116. One of the following is not a reason for the use of an earth mat

  • A. impossibility of a good ground connection
  • B. provision of an earth for the antenna
  • C. protection of personnel working underneath
  • D. improvement of the radiation pattern of the antenna

117. One of the following makes an antenna physically long but electrically short

  • A. Adding L in series
  • B. Adding C in series
  • C. Top loading
  • D. Both A and C

118. When antennas are closed to the ground, _______ polarization is ideal

  • A. horizontally polarized
  • B. vertically polarized
  • C. circularly polarized
  • D. both A and B

119. _____ is an antenna made up of a number of full wavelengths

  • A. Elementary doublet
  • B. Log-periodic
  • C. Long wire
  • D. Whip

120. Any energy which radiates in the form of radio waves, infrared waves, light waves, x-rays, etc.

  • A. Radiant energy
  • B. Electromagnetic
  • C. Heat
  • D. Ultraviolet

121. Which one is an antenna coupling unit?

  • A. Coupler
  • B. Diplexer
  • C. Lecher wire
  • D. Duplexer

122. _____ polarization is employed in AM broadcasting

  • A. Horizontal
  • B. Vertical
  • C. Circular
  • D. Omnidirectional

123. ______ polarization is employed in FM broadcasting

  • A. Horizontal
  • B. Vertical
  • C. Circular
  • D. Bidirectional

124. Which antenna is not grounded at one end?

  • A. Hertz
  • B. Marconi
  • C. Dipole
  • D. Whip

125. Which antenna does not use the ground?

  • A. Marconi
  • B. Yagi
  • C. Hertz
  • D. Rhombic

126. Class of citizens band station operating at 462.55 to 466.45 MHz.

  • a. Class A
  • b. Class B
  • c. Class C
  • d. Class D

127. Ground system recommended by the FCC for broadcast stations consists of a minimum of _______.

  • a. 120 radials
  • b. 150 radials
  • c. 130 radials
  • d. 140 radials

128. To achieve maximum possible energy transfer between transmitting and receiving stations at practical distances, _______ are used.

  • a. High gain
  • b. Parabolic reflector
  • c. Director
  • d. secret

129. ________ is the transmission of data metered at a distance from the observer.

  • a. Data communications
  • b. Altimetery
  • c. Telemetry
  • d. cemetery

130. Impedance transformation between a balanced and unbalanced impedances.

  • a. Gamma match
  • b. Eslun transformer
  • c. Decca match
  • d. Match box

131. Calculate the physical length required of a 146 MHz 4:1 balun mode of polyethylene foam coaxial cable. Use velocity factor of 0.80.

  • a. 12.6 ft
  • b. 2.5 m
  • c. 32.4 inches
  • d. 6.2 inches

132. _______ is an instrument that measures the radiated field from an antenna.

  • a. Field strength meter
  • b. Field meter
  • c. Strength meter
  • d. Intensity meter

133. Calculate the number of turns required to make a 5 uH inductor on a t-50-6 core. Use core factor AL of 40.

  • a. 25
  • b. 35
  • c. 45
  • d. 50

134. This resistance is a hypothetical concept that accounts for the fact that rF power is radiated by the antenna.

  • a. Ohmic resistance
  • b. Resistance
  • c. Radiation resistance
  • d. None of these

135. If 1000 watts of RF power is applied to the feedpoint, and a current of 3.7 amperes was measured, what is the radiation resistance?

  • a. 50 ohms
  • b. 300 ohms
  • c. 600 ohms
  • d. 73 ohms

136. Antenna theory recognizes a point of reference called the _________.

  • a. Half-wave dipole
  • b. Full wave dipole
  • c. Isotropic radiator
  • d. Image antenna

137. Quarter wavelength vertical antenna is basically a dipole placed vertically, with the other half of the dipole being the ____________.

  • a. Gain
  • b. Radials
  • c. Ground
  • d. Reflector

138. Most common form of multi-band wire antenna is the __________.

  • a. Log periodic antenna
  • b. Yagi Uda
  • c. Long wire antenna
  • d. Trap dipole

139. The change in velocity resulting from a stray capacitance is called _________.

  • a. End effect
  • b. Skin effect
  • c. Proximity effect
  • d. No effect

Complete List of MCQs in Communications Engineering per topic

MCQs in Antennas Part III
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